Field of the Invention
The present invention relates to a method for manufacturing a brake disc.
Description of the Related Art
Brake discs are classified into a drum brake type and a disc brake type.
The disc brake type decelerates or stops a vehicle by decelerating or stopping a disc, using friction between a pad and the disc.
Recently, disc types of vehicle brake discs (hereafter, referred to as “brake disc”) are made of a carbon fiber-reinforced ceramic composites.
The carbon fiber-reinforced ceramic composites is a material using ceramic as a matrix and reinforced with a carbon fiber. When a brake disc is made of a carbon fiber-reinforced ceramic composite, it is possible to manufacture a brake disc that is light and having high thermal shock resistance, anti-oxidation, wear resistance, strength, and a friction coefficient.
The applicant(s) have several techniques of manufacturing brake discs using carbon fiber-reinforced ceramic composites and manufactures and selling brake discs made of carbon fiber-reinforced ceramic composites, using these techniques.
On the other hand, when that applicant(s) has sold brake discs, customers have frequently claimed that although there is no problem with the brake discs themselves, there are problems with a pad that comes in contact with the brake discs, a hat part that connects the brake discs to wheels, and a caliper that brings a pad in close contact with the brake discs.
The reasons are as follows.
The brake discs made of carbon fiber-reinforced ceramic composites are lower in density than brake discs made of cast iron, so they are smaller in heat capacity at constant volume than the brake discs made of cast iron. Accordingly, the temperature of the discs increases higher than that of the brake disc made of cast iron due to friction between the pad and the disc in braking. Accordingly, there is no problem with the brake discs that can sufficiently resist high temperature, but pads, hat parts, and calipers around the discs are thermally deformed and deteriorated.
When a pad is thermally deformed and deteriorated, the friction coefficient between a disc and the pad increases in a large range, so uniform braking performance cannot be achieved.
When a hat part is thermally deformed and deteriorated, noise and vibration are generated.
When a caliper is thermally deformed and deteriorated, the caliper cannot accurately bring a pad in close contact with a brake disc, so noise and vibration are generated. Further, when a caliper is heated, brake oil for operating the caliper is boiled, so braking performance rapidly drops.
In order to solve these problems, by making a brake disc made of a carbon fiber-reinforced ceramic composites larger in size than the brake discs made of cast irons, the volume is increased and it is possible to prevent a rise in temperature of a disc.
However, it cannot be a solution because it is impossible to immediately replace a brake disc made of cast iron with a brake disc made of a carbon fiber-reinforced ceramic composites, unless a vehicle is reconstructed.